Phototherapy

According to the German National Disease Management Guideline for unipolar depression, phototherapy is a first-line therapy for SAD patients [13]. Typically, white fluorescent light similar to natural daylight is used, while filtering out ultraviolet radiation. Patients should receive phototherapy 30 to 45 minutes daily at a light intensity of 10 000 lux [14]; ideally, the sessions should be in the mornings as soon as possible after getting up [15]. Typically, phototherapy is administered with a light box placed at a distance of 50 to 80 cm from the patient. Other options are devices which are attached directly to the head – so-called head-mounted units (HMUs) [16] – or phototherapy rooms in which patients spend time. It is important for patients to keep their eyes open during phototherapy since light is processed through a nerve tract referred to as retinopituitary tract [16].

Another form of phototherapy is dawn simulation, which involves gradually brightening the bedroom in which the patient is still sleeping from 0 to 300 lux in the mornings [17,18]. Dawn simulation is easier for patients to integrate into their daily routines, but existing studies have shown it to be less effective than phototherapy with a light box [19,20].

Phototherapy takes a few days or weeks to take effect. It should be continued throughout the winter months since discontinuing phototherapy can lead to a recurrence of depressive symptoms [5].

From the perspective of the general public, the relevant question is whether phototherapy is the effective and safe for the treatment of SAD. Therefore, the present report investigates the effectiveness and safety of phototherapy in comparison with no intervention or different interventions.

Vitamin D therapy

The body’s vitamin D needs are in part met through diet, but most of the vitamin D is produced in the skin when exposed to the sun’s ultraviolet B rays. A small study with 15 SAD patients showed better preliminary results for vitamin D supplements than for phototherapy after 1 week [21]. The National Disease Management Guideline for unipolar depression does not include any recommendations for or against vitamin D therapy in SAD [13]. However, given the importance of this issue to the German public, a systematic review of randomized controlled trials (RCTs) on the efficacy and safety of vitamin D therapy in SAD might provide insights on this topic. In the present report, the efficacy and safety of therapy with vitamin D3 (cholecalciferol), i.e. the most important physiological form of vitamin D, was examined in different pharmaceutical forms (tablets, drops) and dosages.

Second-generation antidepressants

Disturbances of the neurotransmitter system are suspected as a potential cause of SAD [22]. Therefore, SAD is often treated with second-generation antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline reuptake inhibitors, noradrenergic and specific serotonergic antidepressants, selective noradrenaline reuptake inhibitors, or selective noradrenaline-dopamine reuptake inhibitors. According to the German National Disease Management Guideline for unipolar depression, SSRIs and phototherapy are recommended as the first-line treatment of SAD [13]. A Cochrane review on the effectiveness of second-generation antidepressants in the treatment of SAD identified 3 RCTs with the SSRI fluoxetine and found a numerical, but not statistically significant advantage of fluoxetine when compared to placebo [23]. This report does not rely on first-generation antidepressants (tricyclics, tetracyclics, monoamine oxidase inhibitors) as comparators, because their adverse event (AE) profile is worse than that of second-generation antidepressants.

Psychotherapy

Psychological vulnerability can play a role in the development of SAD. Therefore, psychotherapeutic interventions are viewed as potential treatment methods as well [24]. Research focuses particularly on cognitive behavioural therapy [25].

According to the Federal Joint Committee (G-BA) guideline on the conduct of psychotherapy, German statutory health insurance (SHI) covers the cost of the following psychotherapeutic services because the latter are based on a comprehensive theory of pathogenesis and have been proven to be effective in studies: psychoanalytic procedures, behavioural therapy, and systemic therapy [26,27]. This HTA report therefore focuses on these forms of psychotherapy as the comparator intervention.